My advice:
If I knew then, what I know now, I would have sketched, sketched, and sketched some more. Not that I didn’t sketch alot, but there’s always room for more. And remember, you’re not sketching to impress your peers, you’re sketching to uncover ideas. The quicker and more accurately you can do this, the more effective a designer you can become. Oh, and of course, don’t sweat the small stuff while you’re in school, there will be plenty of time for that later. 